Autonomous auxiliary DEF supply system with purge control

ABSTRACT

An auxiliary system automatically supplies diesel exhaust fluid (DEF) to a diesel engine onboard DEF tank to enable prolonged unattended operation. The system includes an auxiliary DEF tank and supply line, a controller, pump, air inlet, and three-way valve configured to switch the pump inlet between the auxiliary DEF tank and air. In response to low-level DEF, the pump delivers DEF to replenish the onboard DEF tank. The controller calculates onboard DEF tank volume based on the delivered volume of DEF, and DEF level data received from an ECM, to enable replenishment control regardless of engine make and model. In response to high-level DEF, engine stoppage, or system fault, the controller switches the pump inlet to air and runs the pump to purge DEF from the supply line. The auxiliary system may be skid-mounted, portable, and configured to supply DEF to multiple diesel engines.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates generally to systems for supplying dieselexhaust fluid (DEF) to diesel engines, and more specifically to anautomated control system for supplying DEF from an auxiliary tank toenable remote, unattended operation of a diesel engine for extendedperiods of time.

Description of Related Art

Diesel engines, whether used to power vehicles, generators, pumps, orcompressors, etc. are subject to environmental standards (e.g. Tier 4Final) that now mandate widespread use of selective catalytic reduction(SCR) technology to reduce harmful nitrogen oxide (NOX) emissions. SCRtechnology injects a urea-based DEF into the exhaust system of a dieselgenerator upstream of a catalyst, where it vaporizes and decomposes toform ammonia and carbon dioxide. The ammonia and catalyst react withNOX, converting it to harmless nitrogen and water.

For standards compliance, DEF supply systems in diesel engines includean onboard DEF tank and controls necessary for causing injection of theDEF into the exhaust system when the engine is running. Diesel enginemanufacturers must provide engine control modules (ECMs) that areprogrammed to automatically shut down the engine, or reduce enginepower, in the event that DEF level or DEF quality drop below acceptablelevels. Timely replenishment of the DEF therefore becomes critical, andso diesel engine operators must refill the onboard DEF tank manually,usually when adding fuel, to replenish DEF that is consumed duringnormal operation. Operators of diesel-powered vehicles such as trucksand tractors are able to maintain an operable level of DEF withoutdifficulty, by topping off the onboard DEF tank during a refueling stop,or by carrying a refill supply on board for emergency use. Operators ofdiesel generators can similarly replenish the onboard DEF tank, providedthat an operator is on duty and able to monitor DEF tank level.

Other problems arise, however, when deploying diesel engines inapplications that require automatic unattended operation. For example,diesel engines are often run in locations remote from an electrical gridto drive stationary apparatus, such as electrical generators, pumps, andair compressors. These applications may require that the diesel enginerun unattended for extended periods of time during which diesel fuel andDEF are continuously consumed. Although extended operation reliesequally on timely replenishment of both diesel fuel and DEF, in practicediesel fuel supplies are generally more readily available to remotelocations than are DEF supplies, due to supply and demand logistics.Periodic replenishment of the DEF tank can therefore become a criticalpath impediment to ensuring compliance with Tier-4 Final (and future)standards for unattended operation of diesel engines for extendedperiods of time.

U.S. Patent Application Publication 2016/0160731 (Turbak et al.)proposes a solution to this problem by providing, for a diesel generatorset, both an onboard DEF tank and an auxiliary DEF supply system. Theoverall system relies on a generator control module, integral to thediesel generator set, to sense DEF level in the onboard DEF tank. Whenthe sensed DEF level is low, the generator control module actuates apump located in the auxiliary DEF supply system to transfer DEF from abulk storage tank to the onboard DEF tank via an auxiliary DEF hose.

The proposed solution of Turbak et al. suffers from severalimpracticalities and leaves other problems unaddressed. For one, DEFreplenishment is controlled by an engine/generator controller thatreceives information from an engine control module (ECM). These controlmodules are customized by the OEM of the diesel generator for use withits particular diesel generator set. Thus, the auxiliary DEF supplysystem lacks independent controls, functions only as a slave to the ECM,and is not designed to interface universally with diesel engines made byother manufacturers. Another problem introduced by this system can occurin the auxiliary DEF hose that carries DEF from the bulk storage tank tothe onboard DEF tank. During time periods when the engine is off and noDEF circulates from auxiliary DEF supply system to the onboard DEF tank,the volume of DEF remaining in the DEF hose can be exposed totemperature extremes for long periods of time and this can adverselyaffect operation. For example, DEF will freeze at about 12 degrees F.Should DEF become frozen in the hose, the auxiliary DEF line may clogand cause a system shut-down. At temperatures above 90 degrees F., thequality of the DEF will begin to degrade and discolor. Discoloration ofDEF can trigger a low-quality alarm, leading to SCR malfunction orsystem shut-down.

What is needed to support prolonged, unattended operation of dieselengines is an auxiliary DEF system with independent local controls thatis capable of interfacing with any make and model of engine and that canoperate autonomously to replenish DEF from an auxiliary tank withoutcompromising DEF quality.

SUMMARY OF THE INVENTION

To address the foregoing problems, the present invention discloses anauxiliary system that automatically supplies DEF to an onboard DEF tankof a diesel engine to enable prolonged unattended operation. A systemaccording to the invention operates autonomously by means of a dedicatedlocal controller that is configured for universal cooperation with ECMsof any make and model of diesel engine. In addition, the inventionprovides a scheme for automatically purging the DEF from an auxiliaryDEF supply line under various operating conditions.

In one embodiment, an auxiliary DEF supply system according to theinvention includes an auxiliary DEF tank, and an auxiliary DEF supplyline configured for fluid communication between the auxiliary DEF tankand an onboard DEF tank of a diesel engine. Also provided are a pump, anair inlet, and a three-way valve. The pump is configured to force fluid(ambient air or DEF) from a pump inlet through the auxiliary DEF supplyline. The three-way valve is configured to switch between a first state,which couples the auxiliary DEF tank to the pump inlet, and a secondstate, which couples the air inlet to the pump inlet. In oneconfiguration of the system, the three-way valve when non-energizedremains in the first state.

A system according to the invention may further include a controllerelectrically coupled to the pump and configured to receive a supplysignal and to command the pump to start in response to receiving thesupply signal. For example, the supply signal may represent low DEFlevel in the onboard DEF tank. The controller may also be electricallycoupled to the three-way valve and configured to receive a purge signal.In response to receiving the purge signal, the controller may commandthe three-way valve to switch to the second state, and command the pumpto stop when a predetermined time period has lapsed after receiving thepurge signal. The predetermined time period is designed to be sufficientto allow the pump to displace the DEF in the auxiliary DEF supply linewith air. Accordingly, in the second state, the pump will force air intothe auxiliary DEF supply line until the supply line is purged of DEF.

The purge signal may be programmed to represent an off state of thediesel engine, a shutdown command for the diesel engine, a high DEFlevel in the onboard DEF tank, or the occurrence of another operatingstate or condition. Signals such as the supply and purge signals may bereceived by the controller of the auxiliary DEF supply system from anECM of the diesel engine via CAN bus protocol. In another embodiment,the controller, in response to receiving the purge signal, may commandthe three-way valve to switch to the first state after the predeterminedtime period has lapsed.

In another embodiment, a single auxiliary DEF supply system according tothe invention is configured for servicing multiple diesel engines. Thissystem is equipped with multiple component trains, wherein eachcomponent train includes a pump, an air inlet, a three-way valve, and anauxiliary DEF supply line—one component train for each engine to beserviced from a common auxiliary DEF tank by a common controller.

In a more elaborate embodiment of the invention, the auxiliary DEFsupply system includes a controller and a portable enclosure, whereinthe controller is configured for communicating via CAN bus protocol, andwherein the portable enclosure contains the controller, the auxiliaryDEF tank, the pump, the air inlet, the three-way valve, and at leastpart of the auxiliary DEF supply line. The enclosure may further includea means for heating or cooling the auxiliary DEF tank.

In another embodiment of the invention, an autonomous auxiliary DEFsupply system for supplying DEF to an onboard DEF tank in a dieselengine includes the following components: an auxiliary DEF tank, anauxiliary DEF supply line configured for fluid communication between theauxiliary DEF tank and the onboard DEF tank, a pump configured to forceDEF through the auxiliary DEF supply line, and a controller electricallycoupled to the pump. According to the invention, the controller isconfigured to command the pump responsive to DEF level signals receivedfrom an engine control module of the diesel engine. In oneimplementation, the DEF level signals are generated according to CAN busprotocol.

In this embodiment the controller is configured to execute a routineencoded in software for calculating onboard DEF tank volume. In oneimplementation, the routine executable by the controller effects thefollowing steps: receiving a low DEF level signal from the enginecontrol module that indicates a low level of DEF in the onboard DEFtank, running the pump for a single fill cycle selected to deliver tothe onboard DEF tank a volume of DEF that is less than a total volume ofthe onboard DEF tank, receiving an actual DEF level signal from theengine control module that indicates a higher level of DEF in theonboard DEF tank, and calculating the total volume of the onboard DEFtank based on the low level of DEF, the delivered volume of DEF, and thehigher level of DEF. In another implementation, the controller mayeffect an additional step for determining a number of the fill cyclesthat will deliver a maximum volume of DEF to the onboard DEF tankwithout exceeding the total volume.

BRIEF DESCRIPTION OF THE DRAWINGS

Other systems, methods, features and advantages of the invention will beor will become apparent to one with skill in the art upon examination ofthe following figures and detailed description. It is intended that allsuch additional systems, methods, features and advantages be includedwithin this description, be within the scope of the invention, and beprotected by the accompanying claims. Component parts shown in thedrawings are not necessarily to scale, and may be exaggerated to betterillustrate the important features of the invention. Dimensions shown areexemplary only. In the drawings, like reference numerals may designatelike parts throughout the different views, wherein:

FIG. 1 is a block diagram of one embodiment of an auxiliary DEF supplysystem according to the invention, coupled to a diesel engine generatorset.

FIG. 2 is a flow chart of one embodiment of a process for a validationroutine executable by an auxiliary DEF supply system according to theinvention.

FIG. 3 is a flow chart of one embodiment of a process for normaloperation of an auxiliary DEF supply system according to the invention.

FIG. 4 is a flow chart of one embodiment of a purge cycle executable byan auxiliary DEF supply system according to the invention.

FIG. 5 is a flow chart of one embodiment of a process executable by anauxiliary DEF supply system according to the invention for monitoringdiesel engine conditions that are capable of triggering a purge cycle.

DETAILED DESCRIPTION OF THE INVENTION

The following disclosure presents exemplary embodiments for an auxiliarysystem that automatically supplies DEF to an onboard DEF tank of adiesel engine to enable prolonged unattended operation. A systemaccording to the invention operates autonomously by means of a dedicatedlocal controller that is configured for universal cooperation with ECMsof any make and model of diesel engine. In addition, the inventionprovides a scheme for automatically purging the DEF from an auxiliaryDEF supply line under various operating conditions.

Diesel engines, often being stationary apparatus, present theopportunity to engineer an independent, portable system for providing anauxiliary service that is common to a wide variety of engines. Whilemodern diesel engines, e.g. those that satisfy Tier 3 and Tier 4 Finalemission control standards, are equipped with ECMs that may beindividually modified to effect the control schemes disclosed herein,the variation in ECM functionality among diesel engine makes and modelsrenders the ECM undesirable for use as a controller in a universalauxiliary DEF supply system. It is therefore an objective of the presentinvention to provide an independent controller for the auxiliary systemthat interfaces physically and functionally with features that allmodern diesel engine control systems have in common. In particular,diesel engines qualified to the Tier 4 Final (and certain other)emissions control standard all utilize the CAN bus protocol to commandthe SCR system. CAN bus signals are used, for example, to monitor DEFparameters, to effect DEF level control and injection, and to satisfyEPA mandates for shutting down the engine via the ECM in response tosensing low DEF levels or low DEF quality. An auxiliary DEF supplysystem according to the invention exploits common features of dieselengine systems by providing an independent controller capable ofexecuting specialized software instructions that interface with any ECMvia known signal protocol to supply DEF from an auxiliary tank whenneeded to support prolonged periods of operation. By reading certainsignals from an ECM in this manner, the auxiliary DEF supply system cansense conditions such as low DEF, and in response turn on an auxiliaryDEF pump, fill an onboard DEF tank from an auxiliary DEF tank, and thenshut down the pump and purge the supply line. A further objective of theinvention is to provide this functionality to multiple diesel generatorsserved from a single auxiliary DEF supply system.

FIG. 1 shows a block diagram of one embodiment of an auxiliary DEFsupply system 10 according to the invention, coupled to a diesel enginegenerator set 30. In the diagram, dashed lines indicate electricalconnections for power and control signals, while solid lines indicatemechanical structure or coupling. In this embodiment, the auxiliary DEFsupply system 10 includes an auxiliary DEF tank 12, an auxiliary DEFsupply line 14, a pump 16, and air inlet 18, and a three-way valve 20.Auxiliary DEF tank 12 is shown partially filled with a quantity of DEF22. In one embodiment, tank 12 may be of stainless steel orthermoplastic construction, and have a capacity of about 100 gallons.

A microprocessor controller 26 is mounted locally on system 10, and iselectrically coupled to control actuation of pump 16, valve 20, and anoptional cooling means 28. In one embodiment, a Parker model MC42 may beused as microprocessor controller 26. The cooling means 28 may be afluid chiller unit or electric fan configured to cool the auxiliary DEFtank 12 and its contents, e.g. in a conventional manner in response tohigh temperature sensed by a temperature sensor (not shown). A heatingmeans 51 may be a heating element or an insulated blanket with electricheat trace, and may be powered from a source of external AC powercoupled to an AC inlet receptacle 41 that is mounted to the enclosure27. A switch or other power connector 39 may be provided to allow theexternal AC power to be conveniently connected to either generator 36 orto utility power 37. The heating means 51 may also include a hose withan integral heating element. Operation of the heating element 51 may becontrolled by the controller 26 in response to sensing low temperaturefrom the temperature sensor.

In a preferred embodiment, the pump 16 is configured to force fluid(ambient air 21 or DEF 22) from a pump inlet 24 through the auxiliaryDEF supply line 14. A Shurflo® model 8000-253-250 diaphragm pump is oneexample of a pump suitable for this purpose. The three-way valve 20 isconfigured to switch between a first state which couples the auxiliaryDEF tank 12 to the pump inlet 24, and a second state which couples theair inlet 18 to the pump inlet 24. An Assured Automation™ modelB33DAXV4F valve is one example of a three-way valve that is suitable forthis purpose. In one configuration of the system 10, the three-way valve20 when non-energized remains in the first state, so that during normaloperation, as described in greater detail below, the system 10 is in aready condition to pump DEF 22 from the auxiliary DEF tank 12 throughthe auxiliary DEF supply line 14 to supply or replenish another DEFtank, such as one that is mounted onboard a diesel engine.

System 10 is shown in a state of use. In this example, system 10 iscoupled electrically and mechanically to a diesel engine and generatorset (DEG) 30. In other applications, system 10 may be coupled tomultiple diesel engines, including for example, engine-generators thatprovide power to different independent loads, or for a paired set ofgenerators powering a common load, or which may be redundant generatorsproviding a source of emergency backup power for a processing plant. Inother applications, system 10 may be coupled to one or more dieselengines that serve as prime movers for pumps, air compressors, or othernon-electrical apparatus.

Diesel engine 34 of DEG 30 represents a fully assembled apparatus thatis commercially available from any of a number of manufacturers such asCummins®, Ford®, John Deere®, Isuzu®, Volvo®, etc. While such apparatusinclude hundreds of components, only a few are shown in the figure andthese are exaggerated for purposes of illustrating salient features ofthe present invention. For example, onboard DEF tank 32, DC battery 38,and ECM 40 appear as separate components but are typically integral tothe system of diesel engine 34. Electrical generator 36 of DEG 30 alsorepresents a fully assembled apparatus, and may be provided separatelyfrom diesel engine 34, or as an integral part of DEG 30.

The auxiliary DEF supply line 14 mechanically connects system 10 tosystem 30. Supply line 14 is configured to maintain fluid communicationbetween the auxiliary DEF tank 12 and the onboard DEF tank 32. In oneembodiment, supply line 14 may be a ⅜ inch inside diameter hose made ofa flexible material such as synthetic rubber and having a nominal lengthof about 25 feet. Other sizes, lengths, and materials for supply line 14are possible within the scope of the invention. Onboard DEF tank 32provides a source of DEF to diesel engine (DE) 34. The diesel engine 34is mechanically coupled to the electrical generator (G) 36. DC battery38 is electrically coupled to the diesel engine 34 in a conventionalmanner to store energy for purposes of starting the engine, and to berecharged by an alternator when the engine is running. The battery 38may provide electrical power to ECM 40. For signal communications, ECM40 is also electrically coupled to the engine 34 and to a dosing controlunit (DCU) 49. The DCU 49 is an OEM device that controls injection ofDEF into the exhaust system of the diesel engine 34 in response toreceiving data representing certain conditions as described herein, suchas the engine 34 running. DCU 49 is electrically coupled to a DEF sensor42 installed within the onboard DEF tank 32. The DEF sensor 42 isconfigured to sense DEF level or DEF quality (or both) in the onboardDEF tank 32. Generally, the DCU 49 receives CAN data from DEF tank 32via a private CAN bus 35 and relays that information to the ECM 40 viapublic CAN bus 25. Signals transmitted to or from DCU 49 may governpurging of the DEF lines 14 after the engine 34 is stopped.

Onboard DEF tank 32 may be a single tank 32 a or 32 b, or for purposesof illustration it may represent multiple DEF tanks that are configuredin fluid communication, such as DEF tank 32 a and DEF tank 32 bconnected together by an equalizing line 44. DEF tank 32 a represents atank style common in certain diesel engine models that has an upper port46 at the top of the tank. DEF tank 32 b represents a tank style commonin certain other diesel engine models that has a port 48 at the bottomof the tank. These ports, however, may already be plumbed for otherpurposes, such as injecting the DEF into the SCR system. According tothe invention, connecting auxiliary DEF supply line 14 to the onboardDEF tank 32 may require a modification to allow for coupling of theauxiliary DEF supply line 14. But the onboard DEF tank, being anessential component in an environmentally qualified SCR system, cannotnormally be modified without disqualifying the system configuration. Anauxiliary system according to the invention must therefore connect viaan auxiliary fill cap port 47 or an existing port—either through a port46 or a port 48—that is not already dedicated for another purpose. Insome cases, where onboard DEF tank 32 comprises multiple tanks 32 a and32 b in fluid communication, one of the ports 46 may be renderedredundant and not used. In that case, the auxiliary DEF supply line 14may take the path of supply line 14 a and connect to a port 46. In othercases, where the port 48 merely serves as a drain plug for maintenancepurposes, the auxiliary DEF supply line 14 may take the path of supplyline 14 b and connect to the port 48. In other cases, the auxiliary DEFsupply line 14 may take the path of supply line 14 c and connect to anauxiliary fill cap with port 47. Note that the three possible paths, 14a, 14 b and 14 c, for the auxiliary DEF supply line 14 are alternativepaths that are superimposed in FIG. 1 for purposes of illustration only.An auxiliary DEF supply system according to the invention needs only onesuch supply line to the onboard DEF tank. At or near the end of supplyline 14 b, an optional check valve 50 may be installed, as shown, toprevent backflow of DEF due to hydrostatic pressure. In one embodiment,a Legris® 48951818 model valve may be used as check valve 50.

System 10 and system 30 are electrically connected between thecontroller 26 and ECM 40. In one embodiment, controller 26, and othercomponents of system 10 electrically coupled to controller 26, mayreceive DC power via the connection to ECM 40. In another embodiment,the controller 26 and the other system 10 components may be powered bydirect connection to generator 36. On a signal level, electricalcoupling between controller 26 and ECM 40 allows controller 26 to reador receive control signals transmitted by ECM 40 that are commonlyrequired in any diesel engine system that is qualified to theenvironmental standards referenced herein. Such signals include DEFlevel and DEF quality in the onboard DEF tank 32. Controller 26 may alsoread any other signal generated by ECM 40, such as the state of anengine ignition switch, the running state of the engine 34 (on or off),the voltage output of battery 38, and an engine fault signal. Inresponse to receiving ECM signals, the controller 26 may be programmedto generate one or more actuation signals to pump 16 or to valve 20 tosupply DEF 22 to the onboard DEF tank 32 or to purge DEF 22 from theauxiliary DEF supply line 14. For example, the controller 26 may beprogrammed to monitor the ECM 40 for certain CAN bus signals known torepresent DEF level in the onboard DEF tank 32. John Deere and CumminsECMs are known to broadcast DEF level using the standard J1939 SAE PGN65110 (FE5 Hex). Isuzu ECMs, however, are known to broadcast DEF levelusing a proprietary PGN 65512 (FFE8 Hex). According to the invention,controller 26 may be programmed to monitor the ECM first for 0xFE56, andif no data is detected after a timeout period has lapsed, beginmonitoring instead for 0xFFE8 as a source for the DEF level data. Inthis manner, controller 26 may be programmed to read CAN bus signalsthat use different message formats to communicate similar data.

A telematics (TM) device 43 may be configured to receive CAN data viapublic CAN bus 25 to enable one form of remote monitoring of system 30.TM 43 received the CAN data and broadcasts relevant informationwirelessly, e.g. using cellular protocol, based on the telematicsprogramming and end user needs.

According to the foregoing system configuration, an auxiliary DEF supplysystem 10 through its controller 26 may read a low DEF signal broadcastby ECM 40, and interpret the data received as a “supply” signal, i.e. asignal indicating that the onboard DEF tank 32 needs to be replenishedwith DEF 22 from the auxiliary DEF tank 12. In response to receiving thesupply signal, the controller 26 according to its programming issues acommand signal to the pump 16 to start. The start command may beeffected according to well-known control techniques, such as controller26 changing voltage at an output pin from low to high to cause a powerrelay to change state and energize the terminals of the pump. With thethree-way valve 20 in the first state, pump 16 delivers DEF 22 to theonboard DEF tank 32 via the supply line 14 to replenish the onboardvolume of DEF.

The controller 26 may be electrically coupled in similar fashion foractuating the three-way valve 20. Other data read from the ECM by thecontroller, such as a high DEF signal, may be interpreted as a “purge”signal, i.e. a signal indicating that the onboard DEF tank 32 is full,and that the auxiliary DEF supply line 14 must be purged of residualDEF. In response to receiving the purge signal, the controller 26 maycommand the three-way valve 20 to switch to the second state, andcommand the pump 16 to stop when a predetermined time period has lapsedafter receiving the purge signal. The predetermined time period shouldbe sufficient to allow the pump 16 to displace the DEF in the auxiliaryDEF supply line 14 with ambient air 21. Accordingly, in the secondstate, the pump 16 will force air into the auxiliary DEF supply line 14until the supply line is purged of DEF. In another embodiment, thecontroller 26, in response to receiving a purge signal, may command thevalve 20 to switch to the first state after the predetermined timeperiod has lapsed. In other embodiments, the purge signal may representan off state of the diesel engine 34, a shutdown command for the dieselengine 34, a high DEF level in the onboard DEF tank, or the occurrenceof some other operating state or condition that warrants evacuation ofDEF from the supply line 14.

In another embodiment of the invention, the auxiliary DEF supply system10 includes a controller 26 and a portable enclosure 27, wherein thecontroller 26 is configured as previously disclosed, and wherein theportable enclosure 27 contains the controller 26, the auxiliary DEF tank12, the pump 16, the air inlet 18, the three-way valve 20, and at leastpart of the auxiliary DEF supply line 14. The portable enclosure 27 mayfurther include a heating means 51, such as an insulated blanket withelectric heat trace. The portable enclosure 27 may further include acooling means 28, such as fluid chilling unit or fan, for cooling theauxiliary DEF tank 12. The system 10 is configured for autonomous,unattended operation by programming the controller 26 for normaloperation (described below) in which the controller continuouslymonitors ECM signals for low and high DEF levels, and in response,automatically cycles system 10 through supply and purge cycles. Barringany operating anomalies, such as engine faults or other componentfailures, system 10 can automatically replenish one or more systems 30with DEF 22 until tank 12 is depleted of DEF or until the diesel enginesrun out of fuel. In another embodiment, a level sensor (not shown) maybe installed in auxiliary DEF tank 12 to monitor the level of DEF 22 andtransmit a level signal to the controller 26. Controller 26 maybroadcast the DEF tank 12 level signal via public CAN Bus 25, to providean operator located remotely from system 10 with the ability to monitorthe state of the system. Other system conditions known to controller 26,such as onboard DEF tank level, running state of the diesel engine,fault signals output by the ECM, number of purge cycles run, etc. can besimilarly transmitted via the public CAN Bus 25. Any of the signalstransmitted by the ECM via the public CAN Bus 25 can also be output viaEthernet port 29 to a remote operator monitoring auxiliary systemoperation, or to a local PC that provides an operator interface forprogramming, setpoint adjustment, and system diagnostics.

In another embodiment of the invention, a single auxiliary DEF supplysystem 10 is configured for servicing multiple diesel engines 34 or DEGs30. This system is equipped with multiple component trains, wherein eachcomponent train includes a pump 16, an air inlet 18, a three-way valve20, and an auxiliary DEF supply line 14—i.e., one component train foreach engine to be serviced from a common auxiliary DEF tank 12 by acommon controller 26. In such an embodiment, the controller 26 is ableto service, simultaneously and independently, diesel engines ofdifferent makes and models, wherein each engine is served in the samemanner as described above as if it were the only engine coupled to theauxiliary DEF supply system.

FIG. 2 shows a flow chart of one embodiment of a process for avalidation routine 200 executable by an auxiliary DEF supply system 10according to the invention as described in the foregoing paragraphs.Validation routine 200 may be performed upon first coupling system 10 toa diesel engine system 30 to allow for automatic determination of thevolume of the onboard DEF tank 32. Once the volume is known, the system10 can store in the memory of controller 26 data representing a numberof “fill cycles” that are required for the pump 16 to deliver DEF 22sufficient to fill the onboard DEF tank 32. A fill cycle is a timeperiod, selected with knowledge of the flow rate of pump 16, duringwhich the pump 16 will deliver enough DEF 22 to allow for detection ofan acceptable rise in onboard DEF tank volume, but not so much DEF 22 asto overflow the smallest known volume of onboard DEF tank (e.g. 7.5gal.) likely to be serviced by system 10. The validation routine givessystem 10 the flexibility to interface universally with any make ormodel of diesel engine by adjusting the number of fill cycles requiredto fill any size of onboard DEF tank. The system 10 can thereforepredict when the onboard DEF tank will become full, and initialize apurge cycle at that point in time, without being reliant on the accuracyof high DEF level signals received from ECM 40.

Validation routine 200 may be stored in software executable by thecontroller 26. The flow chart illustrates the salient steps of theroutine. Validation routine 200 begins at step 202, at which controller26 receives a low DEF level signal from ECM 40 that indicates a lowlevel of DEF (usually 30% of capacity) in the onboard DEF tank 32. Inresponse, in the next step 204, the controller 26 runs the pump 16 forone fill cycle to deliver to the onboard DEF tank a volume of DEF thatis less than a total volume of the onboard DEF tank. In one embodiment,the volume of DEF delivered during the fill cycle is less than or equalto about 70% of tank capacity. For example, given a pump flow rate of 1gpm, and a minimum onboard DEF tank volume of 7.5 gallons, the fillcycle time may be set to 225 seconds. This fill cycle will deliver about3.75 gallons of DEF (or 40% of capacity) into the tank, bringing thetotal volume up to about 75%, which coincides with the typical setpointfor triggering a high level DEF signal. In the next step 206, thecontroller 26 may stop the pump 16 for the duration of a predeterminedstabilization delay, to allow DEF tank volume to stabilize in case DEFtank 32 consists of multiple tanks (e.g. 32 a, 32 b) in fluidcommunication. In the next step 208, the controller 26 reads themeasured level of DEF tank 32 as received from ECM 40, and determineswhether the measured level has reached a minimum validation point, e.g.32% of tank capacity. If it has, the process proceeds to step 210. Atstep 210, the controller 26 calculates the total volume of the onboardDEF tank based on the low level of DEF, the delivered volume of DEF, andthe higher (or measured) level of DEF. In a final step 212, thecontroller determines a number of fill cycles required to deliver amaximum volume of DEF to the onboard DEF tank without exceeding thetotal volume, and stores the number in memory.

If, however, in step 208 the controller 26 determines that the measuredlevel has failed to reach the validation point, e.g. 32% of tankcapacity has not been reached, the process advances to step 214, inwhich an alarm is generated. The alarm may consist of illumination of anLED, generation of an audible tone, and/or broadcasting the failedattempt via public CAN Bus 25, e.g. J1939 CAN Bus. At the next step 216,the controller decides whether a maximum number of failed validationattempts has occurred, by comparing accumulated failures to a thresholdvalue, e.g. three. If the maximum threshold has not been reached, theprocess loops back to step 204 to initiate another fill cycle. If,however, at step 216 the maximum threshold has been reached, the processlogs a validation failure at step 218, and no further fill cycles areperformed. A validation failure may indicate a problem or defect in thesystem, such as a leak, a clogged line, or a component failure. Once avalidation failure is logged, the process may run a purge cycle, as instep 314 below.

In another embodiment of a validation routine, if at step 216 themaximum threshold for fill failures is reached, a fault lightilluminates for the first time and refill routines for DEF tank 32 arelocked out for the duration of the engine run period. If the engine 34stops and is later started again, system 10 will reset the previousfault and restart its normal routines. To illustrate further, if forexample the maximum number of fill failures is set at three: if a firstfill failure occurs at step 214, an internal fault is generated andbroadcast via public CAN bus 25, but the LED alarm is not illuminated.Later if a second fill failure occurs at step 214, a second alarm issimilarly broadcast, but the LED alarm is still not illuminated. Uponoccurrence of a third fill failure at step 214, a third alarm isbroadcast and the LED alarm illuminates to indicate that the system 10will no longer attempt to fill during that particular run cycle. In thiscase, a local operator cognizant of the alarm can troubleshoot thesystem, and a subsequent stopping and restarting of engine 34 will clearthe alarm and enable normal operation.

In another embodiment, in lieu of, or prior to conducting a validationroutine, controller 26 may execute a different routine that firstdetermines the make or model (or both) of engine 34. This may beaccomplished by issuing a query to ECM 40 via public CAN Bus 25, to readdata indicative of engine make and model. Alternatively, the make andmodel may be manually entered by an operator, for example, via port 29by selecting from a menu of choices that each represent a particularmake and model, or class, of engine. The routine can then match theparticular engine make, model, and/or class to a known volume thatcorresponds to the onboard DEF tank of that particular engine, e.g. byconsulting a lookup table.

FIG. 3 shows a flow chart of one embodiment of a process 300 for normaloperation of an auxiliary DEF supply system 10 according to theinvention as described in the foregoing paragraphs. Normal operation isa condition in which system 10 runs automatically without faults orerrors and periodically delivers auxiliary supplies of DEF 22 toreplenish an onboard DEF tank 32 of a diesel engine system 30 that isalso running without experiencing faults or errors that would cause asystem malfunction.

During normal operation of system 10, in decision step 302 thecontroller 26 periodically reads signals from ECM 40 indicative ofwhether the diesel engine 34 is running. If the engine is not running,the process advances to step 304 in which controller 26 maintains thepump 16 in a stopped or deenergized condition. From step 304 the processwill periodically loop back to decision step 302 to assess whether therehas been any change in the state of the diesel engine. If the dieselengine is running, the process advances to decision step 306 todetermine whether a low level DEF signal is being broadcast from ECM 40.If not, then the controller again maintains the pump 16 in a deenergizedcondition at step 304 and the process loops again to step 302, toperiodically monitoring engine state, and possibly again to step 306 tomonitor DEF level in the onboard DEF tank 32.

If the controller 26 reads a low level DEF signal at step 306, theprocess advances to step 308. At this stage the controller 26 energizespump 16 for the duration of a single fill cycle, to pump a minimumvolume of DEF 22 into the onboard DEF tank 32. Next, at step 310, thecontroller 26 stops the pump for the duration of a stabilization delay,to allow DEF level in the onboard DEF tank 32 to stabilize. Next, atdecision step 312, the controller reads data from ECM 40 to determinewhether a high level DEF signal is being broadcast. If not, the processadvances to step 313, to determine whether a maximum number of fillcycles has been reached. If not, the process loops back to step 308 foranother fill cycle. If, however, the controller 26 at step 313determines that a maximum number of fill cycles has been reached, theprocess advances to step 314 to run a purge cycle. If, at step 312, thecontroller reads a high level DEF signal, then the process advances tostep 314 to run a purge cycle.

FIG. 4 shows a flow chart of one embodiment of a purge cycle 400executable by an auxiliary DEF supply system 10 according to theinvention as described in the foregoing paragraphs. The controller 26,upon receiving an indication of a system condition requiring a purge ofauxiliary DEF supply line 14, such as the onboard DEF tank 32 becomingfull as in event 314 in process 300, may execute all or a portion of thesteps of purge cycle 400. The purge cycle begins at step 402, in whichthe controller 26 stops, or deenergizes the pump 16. Next, at step 404,the controller 26 switches the three-way valve 20 to its second statewherein ambient air is presented at pump inlet 24. The next step 406 isan optional step, in which a time delay, e.g. one second, is enforced bythe controller 26 to ensure actuation of valve 20 before actuation ofpump 16. Next, at step 408, the controller 26 energizes the pump 16 fora predetermined, programmable run-time period, e.g. 60 seconds, toensure that all residual DEF 22 is forced out of the auxiliary DEFsupply line 14 and into the onboard DEF tank 32. The final step 410occurs at the end of the run-time period. In step 410, the controller 26stops the pump 16 and deenergizes valve 20 so that it reverts to thefirst state.

FIG. 5 is a flow chart of one embodiment of a process 500 executable byan auxiliary DEF supply system 10 according to the present invention formonitoring multiple diesel engine conditions that are capable oftriggering a purge cycle 400. Process 500 is a model of system operationthat expands on the normal operation process 300 to illustrate how thecontroller of system 10 is configured to monitor for multiple events theoccurrence of any one of which can cause system 10 to change mode fromnormal operation to a purge cycle. Steps 508, 510, 512, and 514 arefunctionally identical to steps 308, 310, 312, and 314, respectively.Steps 516, 518, 520, and 522 are decision steps during which thecontroller 26, while monitoring onboard DEF tank level at step 512, alsomonitors for other purge cycle events. For example, if at decision step512, DEF level is determined not to be full, the controller at decisionstep 516 also monitors the system for a maximum number of fill failure,such as a validation failure in step 218. If a maximum number of fillfailures (e.g. three) is detected, the system runs the purge cycle atstep 514. If no fill failure is detected, the controller at decisionstep 518 determines whether a predetermined maximum pump run time haselapsed. If so, the system runs the purge cycle at step 514. If themaximum pump run time has not elapsed, the controller at decision step520 checks whether the diesel engine 34 is running. If not, the systemruns the purge cycle at step 514. If the engine is running, thecontroller at decision step 522 determines whether the communicationlink with ECM 40 has been lost. If so, the system runs the purge cycleat step 514. Otherwise, process 500 loops back to step 508 to resumenormal operation. Those skilled in the art will recognize that faultsignals or system conditions other than those illustrated in process 500may be monitored by system 10 for purposes of determining, in similarfashion, the operating mode of the system.

Exemplary embodiments of the invention have been disclosed in anillustrative style. Accordingly, the terminology employed throughoutshould be read in a non-limiting manner. Although minor modifications tothe teachings herein will occur to those well versed in the art, itshall be understood that what is intended to be circumscribed within thescope of the patent warranted hereon are all such embodiments thatreasonably fall within the scope of the advancement to the art herebycontributed, and that that scope shall not be restricted, except inlight of the appended claims and their equivalents.

What is claimed is:
 1. An autonomous auxiliary diesel exhaust fluid(DEF) supply system for supplying DEF to an onboard DEF tank in a dieselengine, comprising: an auxiliary DEF tank; an auxiliary DEF supply lineconfigured for fluid communication between the auxiliary DEF tank andthe onboard DEF tank; a pump configured to force DEF or air through theauxiliary DEF supply line; and a controller electrically coupled to thepump; wherein the controller is configured to command the pump to supplythe DEF to the onboard DEF tank in one or more fill cycles responsive toDEF level signals received from an engine control module of the dieselengine, and execute a routine encoded in software for automaticallyrunning a purge cycle to replace DEF in the auxiliary DEF supply linewith air after any one of the fill cycles in response to determining acondition in the system selected from the group consisting of (a) amaximum number of fill failures has occurred, (b) a maximum pump runningtime has occurred, (c) the diesel engine is not running, and (d) loss ofcommunication between the engine control module and the controller. 2.The system of claim 1, wherein the controller is configured forcommunicating via CAN bus protocol.
 3. The system of claim 1, whereinthe pump comprises a positive displacement pump.
 4. The system of claim1, further comprising means for heating contents of the auxiliary DEFtank.
 5. The system of claim 1, further comprising means for coolingcontents of the auxiliary DEF tank.
 6. The system of claim 1, whereinthe auxiliary DEF supply line further comprises a check valve proximatethe onboard DEF tank, the check valve being configured to preventbackflow of DEF through the auxiliary DEF supply line from the onboardDEF tank.
 7. The system of claim 1, further comprising a portableenclosure that contains the controller, the auxiliary DEF tank, thepump, and at least part of the auxiliary DEF supply line.
 8. The systemof claim 7, wherein the portable enclosure further comprises means forheating the auxiliary DEF tank and means for cooling the auxiliary DEFtank, and wherein the controller is configured to command the heatingmeans and to command the cooling means.
 9. The system of claim 1,wherein the controller is configured to run the purge cycle for a presetperiod of time.
 10. The system of claim 9, wherein the preset period oftime is sufficient to allow the pump to displace DEF in the auxiliaryDEF supply line with the air.
 11. The system of claim 1, furthercomprising a three-way valve operably connected to the pump, wherein thethree-way valve is configured to switch between a first state whichcouples the auxiliary DEF tank to a pump inlet, and a second state whichcouples an air inlet to the pump inlet.
 12. The system of claim 11,wherein the controller is electrically coupled to the three-way valve.13. The system of claim 12, wherein the three-way valve whennon-energized remains in the first state.
 14. The system of claim 13,wherein the controller, responsive to receiving a purge signal, commandsthe three-way valve to switch to the second state, and commands the pumpto force air through the auxiliary DEF supply line for a predeterminedperiod of time.
 15. The system of claim 1, wherein the controllerfurther comprises a second routine encoded in software for determining afailure in the system, the controller being configured to execute thesecond routine.
 16. The system of claim 15, wherein the second routinecomprises the steps of: (a) receiving a low DEF level signal from anengine control module of a diesel engine; (b) running the pump for onefill cycle; (c) after completion of the fill cycle and a subsequentpredetermined DEF level stabilization delay, reading an updated DEFlevel signal from the engine control module and comparing the updatedsignal to a validation point; (d) if the updated DEF level signal failsthe comparison to the validation point, determining whether a maximumnumber of similar failures have occurred; and (e) if the maximum numberof similar failures has occurred, stopping the pump.
 17. The system ofclaim 16, wherein the second routine further comprises running the purgecycle after determining the maximum number of similar failures hasoccurred.
 18. The system of claim 1, wherein the controller furthercomprises a third routine encoded in software for calculating onboardDEF tank volume, the controller being configured to execute the thirdroutine.
 19. The system of claim 18, wherein the third routine comprisesthe steps of: (a) receiving a low DEF level signal from an enginecontrol module that indicates a low level of DEF in the onboard DEFtank; (b) running the pump for a single fill cycle selected to deliverto the onboard DEF tank a volume of DEF that is less than a total volumeof the onboard DEF tank; (c) receiving an actual DEF level signal fromthe engine control module that indicates a higher level of DEF in theonboard DEF tank; and (d) calculating the total volume of the onboardDEF tank based on the low level of DEF, the delivered volume of DEF, andthe higher level of DEF.
 20. The system of claim 19, wherein the thirdroutine executed by the controller further comprises: determining anumber of fill cycles that will deliver a maximum volume of DEF to theonboard DEF tank without exceeding the total volume.